Underground Surgeon

Using an array of elixers and poisons, the underground surgeon uses its vast knowledge in the human anatomy to quickly take down their adversaries

Pharmacology

When you choose this archetype at 3rd level, you gain proficiency in the use of both the herbalist and poisoners kit. In addition, as part of a Long Rest, you may use your herbalist kit to create up to four special elixirs. Your elixers remain potent for 24 hours, after which point they become inert and worthless. The number of elixers you can create as part of a Long Rest increases by 1 when you reach 7th Level (5), 13th Level (6), and 19th Level (7).

You also gain advantage on investigation and arcana checks to identify poison and potions

Special Elixer

Utilising one of your prepared elixers you can administer it to yourself or another creature within 5 feet of you. When you administer an elixir, you choose one of the following effects:

Healing - As an Action you inject the target with a healing tonic. The targeted creature restores Hit Points equal to your Sneak Attack damage.
Antidote - As a Bonus Action you inject the target with a cleansing serum. The targeted creature can make an immediate saving throw with Advantage against any one poison or disease currently affecting it.
Stimulant - As a Bonus Action you inject the target with an invigorating tonic. The targeted creature can take the Dash or Disengage action on its next turn as a Bonus Action.

Surgical Presicision

You can use the bonus action granted by your Cunning Action to use and make an Wisdom (Medicine Check) check targeting a creature with a DC equal to its AC to assess its weakesses and how to effectively dissect it. You have advantage on this role against humanoid creatures. On success, you can use Sneak attack against the target even if you don't have advantage on the attack roll as long as you make the attack with a dagger, additionally you may reroll a number of the Sneak attack dice up to your wisdom modifier (minimum 1). You must use the new rolls.

Potent Elixers

At 13th level, your expertise in brewing elixirs has reached new heights.  Your elixers gain the following effects:

Improved Healing - When you roll a 1 or 2 on a healing die, you can reroll the die and must use the new roll, even if the new roll is a 1 or a 2.
Expanded Antidote - The targeted creature can make an immediate saving throw with Advantage against any one poison, disease, or one of the following conditions temporarily affecting it: blinded, charmed, deafened, frightened. On a successful save, the poison, disease, or condition is removed from the target.
Enhanced Stimulant - The targeted creature can take the Dash, Dodge, or Disengage action on its next turn as a Bonus Action and its speed is increased by 10 feet for 1 minute.

Master of Potions and Poisons

At Level 17 your skill in potions and poisons is unparalleled among mortals. When you first create a poison, you can choose to change the poison's damage type to either Necrotic or Acid. Also When a creature you would Poison has immunity to the Poisoned condition, they are instead paralyzed until they take damage or until they succeed a saving throw with a DC equal to the poison's DC. They can repeat this save after each one of their turns. The healings effects of the potions you craft add 2d10 plus your wisdom modifier of temporary hp.

Your elixers Gain the following -
Vigorous Healing - Your healing elixirs provide half of the amount healed as temporary HP.
Perfect Antidote - Your antidotes can now attempt to remove the following additional conditions: paralyzed, petrified, and stunned.
Resiliant Stimulant - The target of your stimulant gains resistance to nonmagical bludgeoning, piercing, and slashing damage for 1 minute.